Determination of Carbonyl Compounds in Workplace Air

Transcription

1 Determination of Carbonyl Compounds in Workplace Air Huang Xiongfeng, Xu Qun, and Jeffrey Rohrer Thermo Fisher Scientific, Shanghai, People s Republic of China; Thermo Fisher Scientific, Sunnyvale, CA, USA Application Note 09 Key Words DNPH-Derivatized Compounds, Aldehyde and Ketone Compounds Analysis, Environmental Analysis, Air Quality, HPLC, Acclaim Carbonyl RSLC Column Goal To develop an efficient high-performance liquid chromatography (HPLC) method for the sensitive determination of,4-dinitrophenylhydrazine (DNPH)-derivatized carbonyl compounds in workplace indoor air samples using a Thermo Scientific Acclaim Carbonyl RSLC column with an ammonium acetate/acetonitrile mobile phase. The target analytes are those specified in California Air Resources Board (CARB) Method 004, International Organization for Standardization (ISO) 6000-:0, U.S. Environmental Protection Agency (EPA) Compendium Method TO-A, and the Chinese HJ/T Introduction Carbonyl compounds are known to cause adverse effects on human health and many of these compounds are listed by the U. S. EPA in the Health Effects Notebook for Hazardous Air Pollutants. Therefore, it is important to establish effective methods for the determination of these compounds. Because HPLC is a frequently used technique, some standard HPLC methods have been created, including EPA Methods 4, 667, 8A, 4 TO-, and TO-A; 6 CARB Method 004; 7 the Chinese HJ/T ; 8 and ISO 6000-:0. 9 Due to the volatility of carbonyl compounds, it is preferable to derivatize them to a nonvolatile stable form, which reduces the possibility of analyte loss and allows the sample to be analyzed later. DNPH is extensively used as a derivatization reagent for such analyses due to its high reactivity, selectivity, and stability of the derivatization products. The reaction yields a chromophore with an absorption maximum of 60 nm, which is suitable for HPLC with UV detection. CARB Method 004 reports an HPLC-UV method for the determination of carbonyl compounds generated by automobiles: formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, methyl ethyl ketone, methacrolein, hexanaldehyde, butyraldehyde, benzaldehyde, valeraldehyde, and m-tolualdehyde. 7 This method requires a primary separation using a C8 column and a secondary separation using a similar column under different conditions because the DNPH derivatives of methyl ethyl ketone and butyraldehyde do not completely resolve with the primary separation. The secondary separation focuses solely on resolving methyl ethyl ketone and butyraldehyde. In HJ/T , DNPH derivatives of acetone and acrolein are difficult to differentiate on conventional C8 columns using acetonitrile/water mobile phases. 8 The addition of tetrahydrofuran (THF) to the mobile phase may resolve the problem in CARB Method 004 and HJ/T because the DNPH-derivatized carbonyl compounds are separated using a CH CN/THF/ H O mobile phase. However, the use of THF in the mobile phase has some limitations for this application, including longer column re-equilibration time following a gradient run, incompatibility with PEEK tubing and seal rings, peroxide formation, and general toxicity.

2 Acclaim Carbonyl RSLC columns are silica-based, reversed-phase columns designed specifically for superior resolution and high-throughput separation of DNPH derivatives of the aldehydes and ketones regulated in the EPA and CARB 004 methods. These columns enable faster analysis with simpler separation conditions when compared to the existing methods (i.e., no THF is needed in the mobile phase). Equipment Thermo Scientific Dionex UltiMate 000 RSLC system, including: LPG-400RS Quaternary Pump with SRD-400 Integrated Solvent and Degasser Rack WPS-000TRS Well Plate Autosampler, Thermostatted, with μl sample loop TCC-000RS Thermostatted Column Compartment DAD-000RS Diode Array Detector with µl flow cell Thermo Scientific Dionex Chromeleon Chromatography Data System software 6.80, SR9 or higher Reagents and Standards Deionized water, 8. MΩ-cm resistivity Acetonitrile (CH CN), HPLC Grade 99.9% (Fisher Scientific P/N AC ) Ammonium Acetate, Crystalline, Certified ACS (Fisher Scientific P/N A67-00) Aldehyde/Ketone-DNPH Stock Standard-, Components in Acetonitrile for CARB Method 004, µg/ml of each component (Cerilliant P/N ERA-0K) Preparation of Solutions and Reagents Working Standard Solutions for Calibration Prepare six working standard solutions for the calibration with 0.0, 0.07, 0.0, 0.7,.0, and.0 µg/ml concentrations by adding the proper amount of aldehyde/ketone-dnph stock standard- and diluting with acetonitrile. Sample Preparation The preparation for workplace air samples (including pretreatment, sampling, and elution) was performed by a third-party inspection institution located in Shanghai, China and followed the standard methods enacted by the Chinese government.,4 Chromatographic Conditions Column: Acclaim Carbonyl RSLC Analytical,. µm,. 0 mm (P/N 07797) Gradient: B min, 48%; min, %;. 4 min, 00% Inj. Volume: µl Temperature: 0 C Detection: UV, 60 nm Results and Discussion Separation of DNPH-Derivatized Carbonyl Compounds Using the Acclaim Carbonyl RSLC Column Figure shows the separation of DNPH-derivatized carbonyl compounds specified in CARB Method 004 using the Acclaim Carbonyl RSLC column and an ammonium acetate/acetonitrile mobile phase. The separation problem of the DNPH derivatives of acetone (Peak ) and acrolein (Peak 4) found in HJ/T is resolved by the Acclaim Carbonyl RSLC column with a calculated peak resolution (R s ) for those two peaks of.67. The Acclaim Carbonyl RSLC column also resolves DNPH-derivatized methyl ethyl ketone (Peak 7) and butyraldehyde (Peak 8) with a R s of. for those peaks, which coelute with the primary separation of CARB Method 004. Complete resolution of the compounds is realized without addition of THF to the mobile phase. 0 Column: Acclaim Carbonyl RSLC,. µm,. 0 mm Gradient: B min, 48%; min, %;. 4 min, 00% Inj. Volume:. µl Peaks:. Formaldehyde. Acetaldehyde 0.0 µg/ml 8. Butyraldehyde 0. Benzaldehyde. Valeraldehyde. m-tolualdehyde. Hexanaldehyde 0.0 µg/ml Figure. Separation of DNPH-derivatized carbonyl compound standards (0. µg/ml each) using the Acclaim Carbonyl RSLC column.

3 Reproducibility, Linearity, and Detection Limits Method precision was estimated by making seven consecutive injections of a calibration standard with a concentration of 0.7 µg/ml for each compound. The retention time and peak area reproducibilities are summarized in Table. Table. Reproducibility for retention time and peak area (n = 7). Table. Method linearity data. Retention Time RSD Peak Area RSD Formaldehyde Acetaldehyde Acetone Acrolein Propionaldehyde Crotonaldehyde Methyl Ethyl Ketone Butyraldehyde Methacrolein Benzaldehyde Valeraldehyde m-tolualdehyde Hexanaldehyde Calibration linearity of the DNPH derivatives of carbonyl compounds was investigated by making three consecutive injections of a mixed standard prepared at six different concentrations (i.e., 8 total injections). The external standard method was used to establish the calibration curve and quantify these DNPH derivatives of carbonyl compounds in the workplace air samples. Linearity was observed from 0.0 to.0 µg/ml when plotting the concentration versus peak area, and the coefficients of determination were for all compounds (Table ). Regression Equation Formaldehyde A =.04c Acetaldehyde A = c Acetone A = 0.749c Acrolein A = 0.896c Propionaldehyde A = 0.796c Crotonaldehyde A = 0.666c Methyl Ethyl Ketone A = 0.7c Butyraldehyde A = c Methacrolein A = 0.64c Benzaldehyde A = 0.448c Valeraldehyde A = 0.9c m-tolualdehyde A = 0.67c Hexanaldehyde A = 0.40c r To estimate method detection limits (MDLs), Figure shows a carbonyl compound calibration standard with a concentration of 0.0 µg/ml for each DNPH derivative separated on the Acclaim Carbonyl RSLC column. These MDLs were estimated using a signal-to-noise ratio (S/N) =. The calculated S/Ns and MDLs are summarized in Table Column: Acclaim Carbonyl RSLC,. µm,. 0 mm Gradient: B min, 48%; min, %;. 4 min, 00% Inj. Volume:. µl Peaks:. Formaldehyde 0.0 µg/ml 8. Butyraldehyde 0.0 µg/ml. Acetaldehyde 0. Benzaldehyde. Valeraldehyde. m-tolualdehyde. Hexanaldehyde Figure. Separation of DNPH-derivatized carbonyl compound standards (0.0 µg/ml each) using the Acclaim Carbonyl RSLC column. Table. S/Ns of DNPH derivatives (0 µg/l each) and calculated MDLs for each compound. Formaldehyde 4 Conc S/N MDL 0..0 Acetaldehyde Acetone. 8.0 Acrolein Propionaldehyde Crotonaldehyde Methyl Ethyl Ketone Methacrolein Butyraldehyde Benzaldehyde Valeraldehyde m-tolualdehyde Hexaldehyde

4 4 Sample Analysis Figure shows a workplace air sample derivatized with DNPH. Formaldehyde and acetone were found, demonstrating the presence of aldehyde and ketone compounds in workplace air. The analysis results are summarized in Table 4. The detected concentration of acetone in the sample is 0 mg/m lower than the permitted amount of 00 mg/m in the Standardization Administration of China (SAC) GB/T whereas that of formaldehyde is 76 mg/m much higher than the permitted 0. mg/m indicating that changes are needed to make the air in this workplace safe for workers. Recoveries for the two detected DNPH derivatives of carbonyl compound standards in the sample exceed 90%, demonstrating good accuracy of the HPLC method. Table 4. Sample analysis results. Detected (mg/m ) Workspace Air Added Found Recovery (%) Permitted in GBZ- 00 (mg/m ) Formaldehyde Acetone Column: Acclaim Carbonyl RSLC,. µm,. 0 mm Gradient: B min, 48%; min, %;. 4 min, 00% Inj. Volume:. µl Samples: A. DNPH-derivatized indoor air sample B. A spiked with a DNPH-derivatized carbonyl compound mixed standard (0. µg/ml each) C. DNPH-derivatized carbonyl compound mixed standard (0.07 µg/ml each) Peaks: C. Formaldehyde. Acetaldehyde 8. Butyraldehyde 0. Benzaldehyde. Valeraldehyde. m-tolualdehyde. Hexanaldehyde Conclusion The work shown here describes an efficient HPLC method with UV detection for the determination of DNPH-derivatized carbonyl compounds in workplace air samples. All carbonyl compounds listed in CARB 004, ISO 6000-, U.S. EPA Compendium Method TO-A, and the Chinese HJ/T are well resolved within min on an Acclaim Carbonyl RSLC column using an ammonium acetate/acetonitrile mobile phase. 0 B A Figure. Overlay of chromatograms of a DNPH-derivatized workspace air sample and spiked samples.

5 References. Health Effects Notebook for Hazardous Air Pollutants, Technology Transfer Network Air Toxics Web Site; U.S. Environmental Protection Agency: Cincinnati, OH, html (accessed May, 0).. Method 4: Determination of Carbonyl Compounds in Drinking Water by Dinitrophenylhydrazine Derivatization and High Performance Liquid Chromatography; U.S. Environmental Protection Agency, National Exposure Research Laboratory, Office of Research and Development: Cincinnati, OH, 99.. Method 667: Formaldehyde, Isobutyraldehyde, and Furfural by Derivatization Followed by High Performance Liquid Chromatography; U.S. Environmental Protection Agency, National Exposure Research Laboratory, Office of Research and Development: Cincinnati, OH, Method 8A: Determination of Carbonyl Compounds by High Performance Liquid Chromatography (HPLC); U.S. Environmental Protection Agency, National Exposure Research Laboratory, Office of Research and Development: Cincinnati, OH, Method TO-: Method for the Determination of Aldehydes and Ketones in Ambient Air Using High Performance Liquid Chromatography (HPLC); U.S. Environmental Protection Agency, National Exposure Research Laboratory, Office of Research and Development: Cincinnati, OH, Compendium Method TO-A: Determination of Formaldehyde in Ambient Air Using Adsorbent Cartridge Followed by High Performance Liquid Chromatography (HPLC) [Active Sampling Methodology]; U.S. Environmental Protection Agency, Center for Environmental Research Information, Office of Research and Development: Cincinnati, OH, California Non-Methane Organic Gas Test Procedures; Method No. 004: Determination of Aldehyde and Ketone Compounds in Automotive Source Samples by High Performance Liquid Chromatography; California Environmental Protection Agency, Air Resources Board: El Monte, CA, 0; pp F- F-9. gov/msprog/levprog/cleandoc/nmogtps_lev%0iii_ clean%0complete_-.pdf (accessed May, 0). 8. HJ/T : Determination of Volatile Organic Compounds and Carbonyl Compounds in Cabin of Vehicles; Ministry of Environmental Protection of the People s Republic of China, Environmental Protection Industry Standards of the People s Republic of China: Beijing, ISO 6000-:0: Indoor Air Part : Determination of Formaldehyde and Other Carbonyl Compounds in Indoor Air and Test Chamber Air Active Sampling Method; International Organization for Standardization (ISO): Geneva, Switzerland, Kim, S. D.; Kim, C. H.; Park, J. S.; Lee, J. J. A Study on the Peak Separation of Acetone and Acrolein Based on High-Performance Liquid Chromatography (HPLC) Method. Bull. Korean Chem. Soc. 009, 0, Thermo Scientific Application Note 06: Determination of Carbonyl Compounds in Vehicle Cabin Compartments. Sunnyvale, CA 0. [Online] webdocs/4679-an06-hplc-carbonyl-compounds -Vehicle-Cabins-AN70_E.pdf (accessed June, 0).. Dionex (now part of Thermo Scientific) Data Sheet: Thermo Scientific Acclaim Carbonyl RSLC Columns. Sunnyvale, CA, 0. [Online] en-us/webdocs/0-ds-acclaimcarbonylrslc- 0Oct0-LPN984.pdf (accessed May, 0).. GB/T 760-0: Guideline for Air Quality Assessment of Passenger Car; Standardization Administration of China (SAC), General Administration of Quality Supervision, Inspection and Quarantine of the People s Republic of China, Beijing, GB/T888-00: Indoor Air Quality Standard; Standardization Administration of China (SAC), General Administration of Quality Supervision, Inspection and Quarantine of the People s Republic of China, Beijing, 00.. GBZ-00: Occupational Exposure Limit for Hazardous Agents in the Workplace; Standardization Administration of China (SAC), General Administration of Quality Supervision, Inspection and Quarantine of the People s Republic of China, Beijing, 00. Application Note Thermo Fisher Scientific Inc. All rights reserved. Cerilliant is a registered trademark of Cerilliant Corporation. All other trademarks are the property of Thermo Fisher Scientific Inc. and its subsidiaries. This information is presented as an example of the capabilities of Thermo Fisher Scientific Inc. products. It is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. Specifications, terms and pricing are subject to change. Not all products are available in all countries. Please consult your local sales representative for details. Australia Austria Belgium Brazil China Denmark France Germany India Italy Japan Korea Netherlands Singapore Sweden Switzerland Taiwan UK/Ireland USA and Canada AN706 _E 07/6S